/*****************************************************************************
 *                                                                           *
 *  This file is part of the BeanShell Java Scripting distribution.          *
 *  Documentation and updates may be found at http://www.beanshell.org/      *
 *                                                                           *
 *  Sun Public License Notice:                                               *
 *                                                                           *
 *  The contents of this file are subject to the Sun Public License Version  *
 *  1.0 (the "License"); you may not use this file except in compliance with *
 *  the License. A copy of the License is available at http://www.sun.com    * 
 *                                                                           *
 *  The Original Code is BeanShell. The Initial Developer of the Original    *
 *  Code is Pat Niemeyer. Portions created by Pat Niemeyer are Copyright     *
 *  (C) 2000.  All Rights Reserved.                                          *
 *                                                                           *
 *  GNU Public License Notice:                                               *
 *                                                                           *
 *  Alternatively, the contents of this file may be used under the terms of  *
 *  the GNU Lesser General Public License (the "LGPL"), in which case the    *
 *  provisions of LGPL are applicable instead of those above. If you wish to *
 *  allow use of your version of this file only under the  terms of the LGPL *
 *  and not to allow others to use your version of this file under the SPL,  *
 *  indicate your decision by deleting the provisions above and replace      *
 *  them with the notice and other provisions required by the LGPL.  If you  *
 *  do not delete the provisions above, a recipient may use your version of  *
 *  this file under either the SPL or the LGPL.                              *
 *                                                                           *
 *  Patrick Niemeyer (pat@pat.net)                                           *
 *  Author of Learning Java, O'Reilly & Associates                           *
 *  http://www.pat.net/~pat/                                                 *
 *                                                                           *
 *****************************************************************************/
package bsh;

class BSHPrimaryExpression extends SimpleNode {

    BSHPrimaryExpression(int id) {
        super(id);
    }

    /**
    Evaluate to a value object.
     */
    public Object eval(CallStack callstack, Interpreter interpreter)
            throws EvalError {
        return eval(false, callstack, interpreter);
    }

    /**
    Evaluate to a value object.
     */
    public LHS toLHS(CallStack callstack, Interpreter interpreter)
            throws EvalError {
        Object obj = eval(true, callstack, interpreter);

        if (!(obj instanceof LHS)) {
            throw new EvalError("Can't assign to:", this, callstack);
        }
        else {
            return (LHS) obj;
        }
    }

    /*
    Our children are a prefix expression and any number of suffixes.
    <p>
    
    We don't eval() any nodes until the suffixes have had an
    opportunity to work through them.  This lets the suffixes decide
    how to interpret an ambiguous name (e.g. for the .class operation).
     */
    private Object eval(boolean toLHS,
            CallStack callstack, Interpreter interpreter)
            throws EvalError {
        Object obj = jjtGetChild(0);
        int numChildren = jjtGetNumChildren();

        for (int i = 1; i < numChildren; i++) {
            obj = ((BSHPrimarySuffix) jjtGetChild(i)).doSuffix(
                    obj, toLHS, callstack, interpreter);
        }

        /*
        If the result is a Node eval() it to an object or LHS
        (as determined by toLHS)
         */
        if (obj instanceof SimpleNode) {
            if (obj instanceof BSHAmbiguousName) {
                if (toLHS) {
                    obj = ((BSHAmbiguousName) obj).toLHS(
                            callstack, interpreter);
                }
                else {
                    obj = ((BSHAmbiguousName) obj).toObject(
                            callstack, interpreter);
                }
            }
            else // Some arbitrary kind of node
            if (toLHS) // is this right?
            {
                throw new EvalError("Can't assign to prefix.",
                        this, callstack);
            }
            else {
                obj = ((SimpleNode) obj).eval(callstack, interpreter);
            }
        }

        // return LHS or value object as determined by toLHS
        if (obj instanceof LHS) {
            if (toLHS) {
                return obj;
            }
            else {
                try {
                    return ((LHS) obj).getValue();
                }
                catch (UtilEvalError e) {
                    throw e.toEvalError(this, callstack);
                }
            }
        }
        else {
            return obj;
        }
    }
}
